Adjustable tint window with electrochromic conductive polymer

ABSTRACT

A method is provided for decreasing radiative heat transfer and adjustably limiting visible light and near infrared radiation transfer and glare through a window. The method comprises the steps of: (a) mounting within a frame of the window a plurality of spaced window panes, a first and second of the panes having opposing faces; (b) assembling between the opposing faces a conductive polymer cell, the cell having a first wall composed of a transparent conductive layer affixed to the first pane and having deposited thereupon an electroactive electro-optically responsive conductive polymer, and a second wall comprised of a transparent conductive layer coated on the second pane, the layer being optionally coated with a second electro-optically responsive polymer, the first and second walls delimiting a cavity containing an ion-conducting electrolyte which contacts opposing surfaces of the first and second walls, and (c) applying a potential between the first and second walls to provide a selected light transmittance upon passage of current therebetween.

This application is a division of application Ser. No. 211,537, filed6/27/88, now U.S. Pat. No. 4,893,908 issued Jan. 16, 1990.

BACKGROUND OF THE INVENTION

This invention relates to the use of a conductive polymer material toselectively control light transmission through a transparent orsemitransparent panel or film, and more particularly to the use of aconductive polymer material to provide a window shade of adjustabletransmittance. Such a device may be embodied as a flexibleadhesive-backed laminated plastic sheet, or as an integral part of amultiple-pane thermal insulating window panel.

Thermal-pane windows conventionally make use of spaced multiple (two ormore) panes to provide a thermal barrier restricting heat conductionbetween the outside and the inside of a building and therefore tendingto reduce heating and cooling costs. To further reduce cooling costs,window shades or blinds are used to block out intense, direct rays ofsunlight, since conventional windows, insulating or otherwise, havelittle effect on radiative heating. However, in using a conventionalshade to eliminate solar glare, the view to the outside is blocked,which may be considered a visually unattractive result. U.S. Pat. No.4,268,126 discloses a multi-pane window unit that uses an electroopticalshade as an integral part of a thermal pane window. Such a device relyson diffuse reflection of light rays to provide mainly privacy. Theeffectiveness of such a window to control radiative heating (solarenergy) is limited by the ability of the window device to reducetransmitted radiation by mainly diffuse scattering and not by opticalabsorption. Devices listed in U.S. Pat. No. 4,268,126 typically reducesolar radiative heating by up to 15%.

Thus, there exists a need for a window unit which includes anelectrooptical device as an integral part of a thermopane window thatprovides a broad adjustable range of coherent light transmittance inboth the visible and near-IR region of the electromagnetic spectrum.Such a window device which relies on absorption rather than diffusereflectance can be used to control glare and the degree of radiativeheating from sun rays while not blocking or obscuring the view from theoutside.

The present invention makes use of conductive polymer material toprovide adjustable control of the intensity of light transmissionthrough a multi-pane thermal window unit or in automobile or aircraftwindows or mirrors where adjustable light transmission is desired. Theroom occupant may select the degree of light transmittance of the shade,thus eliminating glare and the adverse effect on cooling requirementsfrom direct rays of the sun, while not blocking the view to the outside.

Conjugated backbone polymers, e.g., polyacetylene, polyphenylene,polyacenes, polythiophene, poly(phenylene vinylene), poly(thienylenevinylene), poly(furylene vinylene), polyazulene, poly(phenylenesulfide), poly(phenylene oxide), polythianthrene,poly(isothianaphthene), poly(phenylquinoline), polyaniline, andpolypyrrole, and the like have been suggested for use in a variety ofelectronic applications based upon their characteristic of becomingconductive when oxidized or reduced either chemically orelectrochemically. Electrodes composed of such polymers can, accordingto the method of MacDiarmid et al. in U.S. Pat. No. 4,321,114, bereversibly electrochemically reduced to an n-type conductive state (thepolymer being inserted by cations) or reversibly oxidized to a p-typeconductive state (the polymer being inserted by anions).

The electrochemical oxidation or reduction process is generallyrecognized to be accompanied by sharp changes in the color of thepolymer as well as its optical absorption coefficient (its ability totransmit light). Electrochromic devices based on conductive polymershave been described for example by F. Garnier et al. in J. Electroanal.Chem. 148, 299 (1983), by K. Kaneto et al. Japan J. Appl. Phys 22, L412(1983), and by T. Kobayashi et al., J. Electroanal. Chem. 161, 419(1984).

SUMMARY OF THE INVENTION

The present invention provides an electro-optical shade of adjustablelight transmittance as an integral part of a multi-pane thermal windowunit or as a free standing flexible plastic laminate which may beapplied within laminated sheets of glass for automotive and otherapplications, or which may be applied to the surface of an existingwindow or mirror.

Advantageously, the thermal window unit is resistant to radiativeheating and conductive heat transfer between the exterior and interior.Preferably, it consists of substantially parallel, spaced window panes,mounted in a window frame, a first of the panes having affixed theretothe first wall of an electro-optical conductive polymer cell providing aselected light transmittance, and a second of said panes delimiting,with a second wall of said cell a space providing a thermal break. Whenthe device is included as an integral part of a glass laminate, theadvantage of an adjustable tint is obtained from varying the amount andpolarity of direct current applied. The transmission of both visible andnear-infrared radiation can be adjusted.

The term "electro-optical conductive polymer cell" as used hereinafteris intended to means a device consisting of two electrodes with anelectrolyte in between, and at least one of such electrodes comprisingan electrochromic conductive polymer. The conductive polymer materialbeing electro-optically responsive to an applied voltage between theelectrodes, such that light transmittance through the conductive polymermaterial is selectable depending upon the polarity of the appliedpotential and the charge passed through the cell. Additionally, the"electro-optical conductive polymer cell" can contain transparent orsemitransparent electrically conductive layers in contact with theelectrodes, sealant or adhesive layers, support layers comprised, in oneembodiment of the invention, of a plurality of walls of transparent filmhaving sufficient supporting strength to maintain the structuralintegrity of the cell; binders; and polarizer elements, as discussedhereinafter in more detail.

As used herein the term "pane" means a transparent or semitransparent,inorganic or organic material having mechanical rigidity and a thicknessgreater than about 24 microns.

The term "electrically conductive layer" as used herein means a layer orsequence of layers containing an electrically conductive material whichis chemically inert during the operation of the cell. The electricallyconductive layer can consist of a thin semitransparent conductive filmof uniform or of nonuniform thickness or of a sheet-like array ofsubstantially parallel or antiparallel wires.

The window unit may further comprise a window frame means for securingthe mutual orientation of a plurality of transparent, nonintersectingor, preferably, substantially parallel, sequentially spaced panes andfor sealing and isolating a space therebetween; a first transparent panemounted in the window frame means in a position toward an interiorfacing side of said frame means; a second transparent pane,nonintersecting with and, preferably, substantially parallel to andspaced from said first pane, mounted in said frame means in a positiontoward an interior facing side of said frame means; a conductive polymercell comprising in a preferred configuration a first wall composed of asemitransparent electrically conductive layer in contact with anelectrode, a second wall composed of a transparent or semitransparentelectrode and an electrolyte disposed between opposing faces of saidfirst and second walls, at least one of said electrodes beingelectro-optically responsive. Said first wall of said cell being affixedto one of the opposing faces of said first and second panes and saidsecond wall of said cell being affixed to the second pane or for athermal window delimiting with the other opposing face of said first andsecond panes a space providing a thermal break; and an electrical meansfor applying a potential between said conductive layers and saidelectrodes of a selected strength at least sufficient to change theoptical transmission of said conductive polymer material.

The invention further provides a method for decreasing radiative heatingand conductive heat transfer between the exterior and the interior ofthe building, comprising the steps of: mounting within a window frame aplurality of spaced window panes, a first and second of said paneshaving opposing faces; affixing to one of the opposing faces a firstwall of a conductive polymer cell, said first wall being composed of atransparent electrically conductive layer coated with anelectro-optically responsive polymer and cooperating with a second wallcomposed of a transparent electrically conductive layer and, optionally,coated with an electroactive material such as an electro-opticallyresponsive polymer, to form a cavity containing an ion conductingelectrolyte in contact with opposing faces of the first and secondwalls; applying a potential between said first and second walls toprovide a selected light transmittance upon passage of a currenttherebetween; and, optionally, delimiting between said second wall ofsaid cell and the other of said opposing faces of said panes a spaceproviding a thermal break.

Advantageous structural features are provided by the method and means ofthis invention. The conductive polymer cell may be readily produced asfilm on rolls for application to the sizeable area provided by eitheropposing face of the panes. Once applied, a thermal break is achievedwithout need for more than two panes of glass. The size, weight, and thecost of the window unit is markedly reduced, manufacturing proceduresare simplified and the reliability and operating efficiency of the unitare increased.

The panes may be light polarizing to further reduce glare from directsunlight or to increase the efficiency of the polymer cell where theelectrochromic polymer can be also polarized and oriented horizontallyto limit glare or at 90° with respect to an additional polarizingelement to provide enhanced optical absorption characteristics. An inertgas may be injected into the space delimited between the second wall ofthe cell and an opposing face of a pane, or the space may be evacuatedto the extent practical to enhance thermal conductivity breakcharacteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood and further advantages willbecome apparent when reference is made to the following detaileddescription of the preferred embodiment of the invention and theaccompanying drawings in which:

FIG. 1 is a perspective view of a multi-paned window of the presentinvention in a typical frame; and

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1,showing a thermal barrier space between a wall of the electro-opticalconductive polymer cell and an opposing face of a pane;

FIG. 3 is a sectional view showing the details of the electro-opticalconductive polymer cell.

DETAILED DESCRIPTION OF THE INVENTION

Referring specifically to the drawings, in FIG. 1 there is shown awindow unit 1 having two non-intersecting and, preferably, substantiallyparallel, spaced transparent panes 6 and 8 mounted in a conventionalframe 5. A cross-sectional view taken along the line 2--2 in thedirection indicated by the arrows is shown in FIG. 2.

Transparent panes 6 and 8 are mounted in channels 4 of frame 5 with aconventional semi-rigid sealant 9, such as butyl rubber, so that thepanes are non-intersecting and, preferably substantially parallel andspaced. The sealant aids in securing the mutual orientation of thepanes. The window unit is mounted in a window opening of a wallstructure so that the pane 6 is the outside pane and pane 8 is theinside pane. Panes 6 and 8 and the space 10 constitute the thermalpaneportion of the embodiment wherein space 10 provides a thermal barriersignificantly restricting the conduction of heat through the window.Frame 5 is shown as being hollow, by way of example, to restrictperipheral heat conduction and may be an extruded aluminum alloy. Toenhance the thermal barrier effect, space 10 may be evacuated to theextent practical, or filled with an inert gas selected from the groupconsisting of argon, nitrogen, dry air, neon and mixtures thereof. Useof an inert gas, such as argon, inside of the thermal pane can beusefully employed to prevent corrosion or oxidative degradation of theconductive polymer cell, polarizer elements, and adhesive windowcomponents.

Affixed to one of the opposing faces of panes 6 and 8 by means of asuitable adhesive is a first wall 11 of an electro-optical conductivepolymer cell. A variety of adhesives can be conveniently utilized.Preferably the adhesive should thoroughly wet and evenly coat thesurface of the pane and the opposing face of the polymer cell, so as toensure proper bonding and the elimination of spurious void spaces whichcan scatter light and interfere with sound mechanical adhesion. Also,the set adhesive is preferably colorless and either amorphous ormicrocrystalline with a crystallite size much smaller than thewavelength of light, so that negligible light scattering or absorptionof light occurs at the adhesive interface. Adhesives found especiallysuitable for this purpose are certain polyvinylacetate adhesives, orcyanoacrylate adhesives and the like. Wall 11 is composed of atransparent, electrically conductive film, such as tin oxide depositedon a transparent film composed of glass or plastic such aspolymethylmethacrylate, polycarbonates and the like. Wall 11 is coatedwith a thin layer of electro-optical responsive polymer 16 andcooperates with a second wall 7 composed of transparent, electricallyconductive film having the composition of wall 11 and, optionally,coated with an electro active material 17 such as an electro-opticallyresponsive polymer, a transition metal oxide or the like, to form acavity containing a liquid or solid electrolyte material 14. Electricalleads 13 connect the first and second walls 11 and 7 (which constituteelectrodes) to a variable d.c. current supply 15. The electrolytematerial 14 fills substantially the entire volume of the cavity.Typically, the distance between opposing faces of walls 11 and 7 isabout 1-20 mil (25-500.0 microns).

Conductive polymers are intended for use as the primary electrochromicsubstance of which one or both electrodes are comprised. These polymersmay be either anion inserting (p-type) or cation inserting (n-type).Oxidized (p-type) conductive polymers are preferred.

Suitable anion inserting (p-type) polymers include oxidizedpolyacetylene, poly(p-phenylene), polyacene, polyperinaphthalene,poly(phenylene vinylene), poly(thienylene vinylene), poly(furylenevinylene) polyazulene, polynaphthalene, poly(phenylene sulfide),poly(phenylene oxide), polyphenothiazine, polyaniline, polypyrrole,polythiophene, polythianthrene, polyisothianaphthene and substitutedversions of the above. Such polymers may be coated by reaction, whenoxidized, with pyrroles, thiophenes, azulenes, oxiranes, anilines orfurans, as described in commonly-assigned U.S. Pat. No. 4,472,987, thedisclosure of which is incorporated herein by reference.

Among the above listed polymers, those which are substantiallytransparent and colorless in either their oxidized or neutral states(but not both) are preferred. These preferred polymers includepolyaniline in the form referred to as poly(phenylene amine) andpolypyrrole which are transparent in their neutral state, andpoly(alkoxythienylene vinylene) and polyisothianaphthene which aresubstantially transparent in their oxidized state. Most preferred arepoly(phenylene amine) and poly(alkoxythienylene vinylene).

Suitable cation inserting (n-type) polymers include poly(p-phenylene),polyacetylene, poly(p-phenylene vinylene), and poly(phenylquinoline)which are preferred. Most preferred is poly(phenylquinoline) and itssubstituted derivatives.

Polymers suitable for this invention may also contain electrochromicsubstituent groups such as viologens and the like to enhance theintensity of the changes in optical and infrared absorption.

Since it is critical that the device of this invention be capable of alarge number of cycles between states of varying transmissiveness, thedevice must be provided with two electrodes at which fully reversibleelectrochemical reactions occur. These electrodes must be separated by asolid or liquid electrolyte which is ionically conductive butelectrically insulating. The components of this electrolyte must ingeneral be electrochemically inert but there may be certain embodimentsthat contain species which undergo reversible reactions at one or bothelectrodes.

While only one of the two electrodes of the electro-optical cell need becomposed of an electrochromic material, advantage in contrast andefficiency is obtained if both electrodes operate in tandem. In thiscase, a given polarity of the voltage applied to the cell causes bothelectrodes to become simultaneously deeply colored or absorbing in thevisible or infrared or both. The opposite polarity applied to the cellcauses both electrodes to become optically transmissive in the visibleor infrared or both. The efficiency of the device is further improved byorienting the polymers 16 and 17 on their supports (11, and 7 in FIGS.2,3) such that the polymer chain orientation of opposing electrodesdiffers by 90°. Cross-polarization then further limits the transmissionof light when the polymers are in their absorbing state. The polymerscan be oriented to achieve a polarization of light by drawing of thesubstrate (for a polymer substrate) after the conductive polymer isdeposited, by grooving the substrate prior to deposition, by imposing ashear during electrochemical polymerization or by other chainorientation methods.

We can arbitrarily classify materials for the electro-optical cell asanode or cathode materials based on their becoming transmissive duringan anodic or cathodic process, respectively. That is, an anode materialis defined as a material that becomes transmissive during an oxidationprocess and becomes optically absorbing during a reduction process. Thereverse would apply for a cathode material.

Tables 1 and 2 list a number of anode and cathode materials useful forthe construction of the electro-optical cell of this invention. In apreferred embodiment, one electrode would be composed of a material fromTable 1 and the opposing electrode would be composed of a material fromTable 2. In these preferred embodiments, the device in its visiblytransmissive state would be substantially colorless (with very lightblue, green or yellow tint). Other polymers included in the broaddescription of useful polymers could be employed for devices designed toprovide distinct color transformations such as blue to red or green tored along with changes of transmitted light intensity.

                  TABLE 1                                                         ______________________________________                                        Materials for Use as the Anode.sup.(a)                                                        Film Preparation                                                                           Redox State of                                   Materials       Method.sup.(b)                                                                             Colored Form                                     ______________________________________                                        poly(alkoxythienylene                                                                         SC           neutral                                          vinylene)                                                                     polyisothianaphthene                                                                          E            neutral                                          Tungsten bronze (WO.sub.3)                                                                    CVD          reduced (cation-                                                              inserted)                                        Molybdenum bronze (MoO.sub.3)                                                                 CVD          reduced (cation-                                                              inserted)                                        poly(phenylquinoline)                                                                         SC           reduced (cation-                                                              inserted)                                        poly(p-phenylene)                                                                             E            reduced (cation-                                                              inserted)                                        polyacetylene   P            neutral                                          ______________________________________                                         .sup.(a) Materials which become transmissive during an anodic process         (oxidation)                                                                   .sup.(b) E = electrochemical polymerization SC = solution cast CVD =          chemical vapor deposition p = direct chemical polymerization onto             substrate                                                                

                  TABLE 2                                                         ______________________________________                                        Materials for use as the Cathode.sup.(a)                                                    Film Preparation                                                                            Redox State of                                    Material      Method.sup.(b)                                                                              Colored Form                                      ______________________________________                                        poly(phenylene amine)                                                                       E,SC          oxidized (anion-                                                              inserted)                                         polypyrrole   E             oxidized (anion-                                                              inserted)                                         poly(p-phenylene                                                                            SC            oxidized (anion-                                  vinylene)                   inserted)                                         polyacetylene P             neutral polymer                                   ______________________________________                                         .sup.(a) Materials which become transmissive during a cathodic process        (reduction).                                                                  .sup.(b) Eelectrochemical polymerization SC = solution cast P = direct        polymerization onto substrate                                            

It is also possible to construct an electro-optical cell using only oneof the materials from either Table 1 or Table 2. One of the electrodeswould then be composed of a continuous film of a conductive polymer andthe opposing electrode would either be composed of narrow strips of thesame polymer or of a largely transparent conductive material which doesnot appreciably change its optical absorption characteristics but whichprovides a substrate for, or itself undergoes a reversibleelectrochemistry. In this embodiment, an electroactive species might beincluded in the electrolyte. Such species include FeSO₄. When such anelectroactive species is included in the electrolyte a semipermeable orselective diffusion barrier might be provided between the two electrodesto improve the stability.

The solvents which may be included in the electrolyte of theelectro-optical cells of the present invention may vary widely and canbe organic solvents or aqueous solvents normally used forelectrochemical oxidations or reductions. Preferably, these solventsshould be electrochemically inert to oxidation and reduction during usewhile simultaneously being capable of dissolving the desired salt at aconcentration of preferably about 0.1M and more preferably about 1M,capable of wetting the polymer, and providing an ionic conductivityabout equal to or in excess of about 10⁻⁵ S/cm, preferably about equalto or greater than about 10⁻⁴ S/cm more preferably about 10⁻³ S/cm.Examples of such useful solvents include propylene carbonate, ethylenecarbonate, sulfolane, methylsulfolane, butrolactone, dimethylsulfolane,3-methyl-2-oxazolidone, alkane sultones, e.g., propane sultone, butanesultone, dimethyl sulfoxide (DMSO), dimethyl sulfite, acetonitrile,benzonitrile, methyl formate, methyltetrahydrofurfuryl ether,tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MTHF), dioxane,dioxolane, 1,2-dimethoxyethane (DME), dimethoxymethane, diglyme andglymes, and water. Mixtures of such available organic solvents may alsobe used, such as mixtures of sulfolane and dimethoxyethane, or mixturesof propylene carbonate and dimethoxyethane, or mixtures of water andacetonitrile, benzonitrile and aqueous perchloric acid, acetone andwater, and the like.

The solvents chosen for use in any particular situation will, of course,depend upon many factors such as the precise electrolyte compositionused and the voltage range desired as well as the choice of electrodesand other components.

In a preferred embodiment, the solvent may also be replaced by a polymerwhich is capable of conducting ions. Such polymers include those inwhich an acid, base, or salt may be dissolved to form an ion conductingmedium. These polymers include but are not restricted to poly(vinylalcohol), poly(ethylene oxide), poly(propylene oxide), polysiloxane,poly(alkoxyphosphazines), and mixtures thereof.

Also included are polymers which form gels with or may be swollen byaqueous or nonaqueous solvents. Such polymers may vary widely andinclude polyacetates, poly(vinylalcohal) polydiacetylenes, polyethylene,and the like, and copolymers or terpolymers such asethylene-propylene-diene terpolymer (EPDM).

Salts for use in the electro-optical device of this invention may varywidely but must be ionizable in the solvent chosen and must providesuitable counterions for the oxidized or reduced conductive polymersemployed as electrochromic materials.

In the case of oxidized (p-type) conductive polymers the anion of thesalt must be capable of insertion into the polymer during oxidationwithout decomposition. Suitable anionic species include I⁻, I⁻ ₃, Br⁻,Cl⁻, ClO₄ ⁻, PF₆ ⁻, BF₄ ⁻, AlCl₄ ⁻, FeCl₄ ⁻, HF₂ ⁻ fluorinatedorganoborates, and organofluoroborates, such as B(p--FC₆ H₄)--₄ and B(C₆F₄)₄ ⁻, sulfonates, such as CF₃ SO⁻ ₃, CF₃ (C₆ H₄)SO₃ ⁻, C₆ H₅ SO₃ ⁻ andCH₃ (C₆ H₄)SO₃ ⁻, POF₄ ⁻, CN⁻, SCN⁻, CF₃ CO₂ ⁻ (trifluoroacetate), C₆ H₅CO₂ ⁻ (benzoate), HSO₄ ⁻ and the like.

In the case of reduced (n-type) conductive polymers the cation of thesalt must be capable of insertion into the polymer during reductionwithout decomposition. Suitable cationic species include Li⁺, Na⁺, K⁺,Rb⁺, Cs⁺, alkylammoniums such as (CH₃)₄ N⁺, (C₂ H₅)₄ N⁺, (C₃ H₇)₄ N⁺,(C₄ H₉)₄ N⁺, (CH₃)(C₃ H₇)₃ N₊, as well as sulfonium and phosphoniumanalogs and the like, and cyclic ions such as pyridinium, imidazolium,and the like. Particularly preferred are the alkali-metal ions.

For devices which contain only p-type or only n-type polymers, the ionthat remains in solution and which is not inserted must be inert tooxidation and reduction, respectively. Preferred anions for use in thepresence of reduced polymers are PF₆ ⁻, alkylborates and arylborates(U.S. Pat. No. 4,522,901), and halides. Preferred cations for use in thepresence of oxidized conductive polymers are the alkali-metal ions,protons, and silver ions.

Room-temperature molten salts may also be useful as electrolytes in thepresent invention. Such salts include alkylimidazoliumtetracholoraluminates (the use of which for the oxidation and reductionof conductive polymers is described in U.S. Pat. Nos. 4,463,071 and4,463,072), alkylpyridinium tetrachloroaluminates, and mixtures of theabove with alkali-metal halides.

A variety of transparent conductors, such as SnO₂, InO₃ and Cd₂ SnO₄ andthe like, can be used for the conductive surface on walls 7 and 11 (seeFIGS. 2 and 3). Examples of commercial compositions for such conductorsare transparent metal oxides made by Deposition Technology andSierracin/Intrex using sputtering techniques involving reactive gases incombination with metal targets. Leybold-Heraeus also offers commerciallya metal/metal oxide coating called TCC 2000 which is sufficientlytransparent and conductive for the present application.

EXAMPLES OF THE INVENTION Example 1

Poly(phenylene amine) electrodes were fabricated by electrochemicallyoxidizing acidic aqueous solutions of aniline. A solution containing0.5M aniline, 0.5M NaHSO₄, and 0.6M H₂ SO₄ was found to be preferredover solutions containing Cl⁻ or CH₃ SO₃ ⁻ anions in place of HSO₄ ⁻.Galvanostatic deposition of the polymeric film on ITO conducting glass(a glass, D, coated with an indium-tin oxide conductive layer, E, inFIG. 1) was accomplished by imposing a constant current of 0.35 mA/cm²between the ITO electrode and a nickel screen counter electrode until atotal charge of 70 mC/cm² had passed. This procedure produced a veryuniform, adherent film of electrooptic polyphenylene amine on the ITOglass.

Example 2

A window containing an electro-optical cell was assembled as in FIG. 1from an electrode with a poly(phenylene amine) deposit as described inExample 1 and a second piece of ITO conducting glass separated by aspacer of an inert material, teflon, with the intervening space beingfilled with a liquid electrolyte solution of 1.0M H₂ SO₄. When acathodic current was applied to the electrode with the poly(phenyleneamine) deposit the window become highly transmissive. When an anodiccurrent was applied to the electrode with the polymeric deposit thewindow became highly absorbing with a dark green-blue coloration.

Example 3

A window containing an electro-optical cell was assembled as in Example2 except that the electrolyte was a gel consisting of a 20 wt % aqueoussolution of poly(vinyl alcohol) and 1.1M H₃ PO₄. When a cathodic currentwas applied to the electrode with a poly(phenylene amine) deposit thewindow became transmissive. When an anodic current was applied to theelectrode with the polymeric deposit the window became highly absorbing.Repeated cycling, however, caused a brownish discoloration of the windowwhich was found to be caused by the lack of a reversible couple at theelectrode composed only of ITO glass.

Example 4

A window was assembled as in Example 3 except that the gel electrolytecontained ferrous sulfate (1 mM) and ferric sulfate (1 mM), anelectrochemically reversible couple which moderated the cell voltage andserved as a substrate to take up and release charge as the polymericelectrode was being charged. When a cathodic current was applied to theelectrode with the poly(phenylene amine) deposit, the window becametransmissive. When an anodic current was applied to the electrode withthe polymeric deposit the window became highly absorbing. Repeatedcycling was achieved without the discoloration observed in Example 3.

Example 5

A window was assembled as in Example 3 except that the electrolyte was asolid transparent film made by applying a 20 wt. % aqueous solution ofpoly(vinyl alcohol) and 1.1M H₃ PO₄ to the electrode having thepolymeric deposit of poly(phenylene amine) and evaporating the water at35° C. for 24 hours. When a cathodic current was applied to theelectrode with the poly(phenylene amine) deposit the window becometransmissive. When an anodic current was applied to the electrode withthe polymeric deposit the window became highly absorbing.

We claim:
 1. A window unit having an electro-optical shade of adjustablelight transmittance comprising:(a) window frame means for securing themutual orientation of a plurality of transparent, substantiallyparallel, sequentially spaced panes; (b) a first transparent panemounted in said window frame means in a position toward and interiorfacing side of said frame means; (c) a second transparent panesubstantially parallel to and spaced from said first pane, mounted insaid frame means in a position toward an interior facing side of saidframe means; (d) a conductive polymer cell comprising a first wallcomposed of a semitransparent electrically conductive layer in contactwith an electrode comprising an electroactive electro-opticallyresponsive conductive polymer composed of either p-type (anion inserted)or n-type (cation inserted) conjugated polymers, a second wall composedof a transparent or semitransparent electrode optionally comprising asecond electro-optically responsive conductive polymer, said conjugatedpolymers being chain oriented in a plane parallel to the plane of thewindow so as to create a polarization of the transmitted light, and anelectrolyte disposed between opposing faces of said first and secondwalls; (e) said first wall of said cell being affixed to one of theopposing faces of said first and second panes; and (f) electrical meansfor applying a potential between said conductive layers and saidelectrodes of a selected strength at least sufficient to change theoptical transmission of said conductive polymer.
 2. A window unit asrecited in claim 1, further comprising a third pane mounted in saidwindow frame means and delimiting, with said first or second panes, aspace providing a thermal break.
 3. A window unit as recited in claim 2,comprising sealing means for sealing isolating said space.
 4. A windowunit as recited in claim 3, wherein said space has disposed therewithinan inert gas to enhance thermal break characteristics.
 5. A window unitas recited in claim 4, wherein said inert gas is selected from the groupconsisting of argon, nitrogen, dry air, neon and mixtures thereof.
 6. Awindow unit as recited in claim 1, wherein said p-type conjugatedpolymers are coated on said first wall and are adapted to becometransmissive during a reductive or cathodic process.
 7. A window unit asrecited in claim 1, where said p-type conjugated polymers are coated onthe second wall and are adapted to become transmissive during anoxidative or anodic process.
 8. A window unit as recited in claim 1, inwhich said p-type conjugated polymers are chosen from poly(thienylenevinylene), poly(furylene vinylene), poly(isothianaphthene),polyacetylene, and substituted versions thereof.
 9. A window unit asrecited in claim 8, in which said poly(thienylene vinylene) issubstituted in the 3 position by a methoxy, propoxy, butoxy, hexoxy, oroctyloxy group.
 10. A window unit as recited in claim 1, wherein saidn-type conjugated polymers are coated on said second wall.
 11. A windowunit as recited in claim 10, wherein the n-type conjugated polymer ischosen from polyacetylene, poly(p-phenylene),poly-2,6-(4-phenylquinoline), and substituted versions thereof.
 12. Awindow unit as recited in claim 1, wherein said second electro-opticallyresponsive material is coated on said second wall as an electroactivematerial, and is adapted to become transparent during an oxidative oranodic process.
 13. A window unit as recited in claim 12, wherein saidsecond electro-optically responsive material is a tungsten bronze or amolybdenum bronze.
 14. A window unit as recited in claim 13, whereinsaid bronze is applied to the conductive layer of claim 1 as asubstantially amorphous film.
 15. A window unit as recited in claim 1,wherein the plane of polarization is chosen to be horizontal with theground and substantially eliminates glare.
 16. A window unit as recitedin claim 1, wherein the conductive polymers applied to each of saidfirst and second walls are respectively chain oriented in perpendiculardirections so as to effect a cross polarization of transmitted light.17. A window unit as recited in claim 1, wherein said electrolyte iscomposed of an ionizable salt dissolved in a liquid solvent.
 18. Awindow unit as recited in claim 1, wherein said electrolyte is composedof a solid polymeric electrolyte.
 19. A window unit as recited in claim18, wherein the polymeric electrolyte is composed of a mixture ofphosphoric acid and poly(vinylalcohol).
 20. A window unit as recited inclaim 18, wherein the polymeric electrolyte is composed of a mixture ofan alkali-metal salt and a saturated polyether or other backbone polymerhaving polyether side groups.
 21. A window unit as recited in claim 1,wherein the transparent conductive layer of the first and second wallsis composed of indium-tin oxide, antimony-tin oxide or cadmium-tinoxide.
 22. A window unit as recited in claim 1, wherein the oppositeface of the pane forming the first and second wall is covered by areflecting coating to form a mirror providing an adjustable degree ofreflection.